Process for the regulation of the flow in conduits

ABSTRACT

The pitch of orientable blade pumps at various stations along a pipeline and valving at the stations are regulated to conform pressures and flow rates in the pipeline to accommodate the upper limits tolerable in the section under most stress compared to its capability. The process is especially useful where fluids of differing viscosity are to be successively pumped. By preference, the process is practiced to provide an output at the delivery terminal with either a constant flow rate or a constant arrival head. The process also accounts for start-up conditions and extinction of propagation of hammering effects.

United States Patent 1 1 1111 3,844,673 Hayward Oct. 29, 1974 PROCESS FOR THE REGULATION OF THE 3,292,846 12/1966 Harper et al 415/1 FLOW IN CONDUITS 3,767,318 l0/I973 Shirato 4l5/l 3,773,429 ll/l973 Hayward 4l5/ll [76] Inventor: Pierre P. Hayward, 6 Rue des a i 7 l I Ecoles 92 Samt C W France Primary Exammerl-lenry F. Raduazo [22] F1led: Oct. 17, 1973 Attorney, Agent, or FirmCushman, Darby & 21 Appl. No.: 407,056 Cushma" Related US. Application Data [63] Continuation-impart of Ser. No. 127,506, March 24, [57] ABSTRACT 1971 The pitch of orientable blade pumps at various stations along a pipeline and valving at the stations are [30] Fore'gn Apphcauon Pnomy Data regulated to conform pressures and flow rates in the M211. 24, France pipeline to accommodate the upper tolerable in the section under most stress compared to its capabil- U-S. The process is especially useful where fluids of 415/26 fering viscosity are to be successively pumped. By [5 Cl. preference the process is practiced to provide an out- Field of Search 415/1, 26, 48, put at the delivery terminal with either a constant flow 45/129, 130 rate or a constant arrival head. The process also accounts for start-up conditions and extinction of propa- [56] References Cited gation of hammering effects.

UNITED STATES PATENTS 9/1966 McCracken 415/26 11 Claims, 6 Drawing Figures SHEH 2 BF 5 MQDMMMQQ l mkbmwwkk PATENTED 0137 29 #974 PROCESS FOR THE REGULATION OF THE FLOW IN CONDUITS REFERENCE TO RELATED CASE The present application is a continuation-in-part of application No. 127,506, filed Mar. 24, 1971 now U.S. Pat. No. 3,773,429, issued Nov. 20, I973.

FIELD OF THE INVENTION The present invention relates to a process for regulation of the flow in liquid conduits, for example in pipelines.

BACKGROUND OF THE INVENTION So far, transportation in pipelines is effected by means of pumping groups in stations strung out along the pipelines, the pumps being of the centrifugal type. It is known that in pipelines the operation of the whole is most often conditioned by the situation that prevails in the pipeline section where flow is effected in the most unfavorable way, this section moreover varying in one single pipeline according to the characteristics and especially the viscosities of different liquids that pass through the pipeline in succession. As a result pressure and outputs effected by the pumping groups must frequently vary. These variations are actually caused either by creation of supplementary head losses or by variation of pump speed, for example by speed variators. In both cases, there is a considerable dissipation of energy, the more so if the different pumps then operate with outputs imposed by the ensured head and flow, often far from the maximum yields of the pumps.

For sizeable variations of flow, pumping groups are started (or stopped) in parallel or in series. Starting up or stopping these pumping groups is abrupt, and this is expressed by a loss of energy in transitory regimes, also causing mixture of liquids across the interface of origin. On the other hand, because of this lack of flexibility, it is difficult to take effective measures against incidents such as hammer. In general, when there is hammer, it is necessary to stop difierent pumping groups, which shows up upstream in a cumulative effect at the level of each station which can entail deterioration in the pipeline.

To resolve this problem, there has been provision according to the aforesaid copending U.S. patent application Ser. No. 127,506 for conduits or pipelines comprising at least one pumping station with at least one pump having at least one stage: said pump comprising blades inclined on a truncated cone coaxial with the axis of the rotor, and means, including servo motors, to pivot said blades, as well as means for measuring hydraulic flow parameters, and regulation means sensitive thereto to act on said servo motors.

In a preferred embodiment of such pumps that is applicable especially to pipelines, these pumps with their servo motors and their drive motors are disposed in pumping stations distributed along the pipeline according to the geographical configuration thereof, each pumping station having a flow sensor, sensors for suction and discharge pressures, and possibly a density sensor and a viscosity sensor. The means for regulation which act on the servo motors to cause the pump rotor blades, or equivalent pivotable blades on the pump housing, to pivot have electric transmitters or other devices which allow them to receive the measurements of the said sensors, said control means also comprising devices which allow comparison of data received from the sensors with reference data posted from the outside, e.g. flows and/or imposed pressures.

It is readily understood that for a given rate of rotation it is possible, by acting on the inclination of the blades, to adapt the pumps to ensure flow and a given pressure. As shown by FIG. 4 of the drawings, abscissa O represents the flow in m per second, and ordinate H the head in meters of water. Curves i= 0 to i= 25 represent the characteristics for the different values of angle i of inclination of the blades. Curves 42 to 89 represent the curves of constant yield.

SUMMARY OF THE INVENTION The pitch of orientable blade pumps at various stations along a pipeline and valving at the stations are regulated to conform pressures and fiow rates in the pipeline to accommodate the upper limits tolerable in the section under most stress compared to its capability. The process is especially useful where fluids of differing viscosity are to be successively pumped. By preference, the process is practiced to provide an output at the delivery terminal with either a constant flow rate or a constant arrival head. The process also accounts for start-up conditions and extinction of propagation of hammering effects.

The process of the invention is used in conduits or pipelines comprising at least one pumping station with at least one pump having at least one stage, each pump comprising a casing, a rotor, hearings to support the rotor in rotation about its longitudinal axis in the easing, means to turn the rotor about said axis, a plurality of blades disposed between the rotor and the casing, shaft means for mounting of each blade on the rotor for a movement of pivoting about its longitudinal axis, the said shaft means collectively having their longitudinal axes disposed on a cone of revolution coaxial with the rotor, means associated with the said rotor including servo motors to pivot said blades with reference to the rotor about said axes, means for measurement of hydraulic flow parameters disposed in said conduit, and means for regulation connecting the measurement means to the servo motors to effect a pivoting movement of the blades in response to the measurements effected by said measurement means.

The angle of the apex of said cone may vary widely, even reaching a zero value, but preferably said angle is between 30 and I An object of the present invention is to provide processes which allow ensurance of the regulation in conduits and especially pipelines, eliminating throttle elements such as the control valves used thus far to ensure regulation, and correspondingly eliminating energy losses due to the functioning of the said means of regulation. I

Another object of the present invention is to provide processes that ensure regulation without variation of the speed of the pump drive motors in a conduit.

Another object of the invention is to provide a pro-' cess that ensures regulation not only avoiding losses, but even increasing the output of the pumping means.

Another object of the invention is to provide a pro-. cess that ensures flow regulation duringstart up of the pumping station or stations, reducing the power necessary for start up and producing a regular development of output.

Another object of the invention is to increase the reliability of functioning of a conduit, especially a pipeline, effecting a regulation that is adapted to water hammer deriving from an excess pressure surge.

The principles of the invention will be further hereinafter discussed with reference to the drawings wherein preferred embodiments are shown. The specifics illustrated in the drawings are intended to exemplify, rather than limit, aspects of the invention as defined in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS In The Drawings:

FIG. 1 shows schematically a pipeline with decentralized control;

FIG. 2 shows schematically the hydraulic curves associated with the said pipeline;

FIG. 3 shows schematically a pipeline with centralized control;

FIG. 4 shows the characteristic curve of a variable blade pump;

FIG. 5 shows the characteristic curve of a start-up sequence of a station also comprising standard-type centrifugal pumps; and

FIG. 6 shows a detailed schematic view of a pumping station of the pipeline of FIG. 1.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS OF THE INVENTION Reference is made to FIGS. 1 and 2.

A pipeline is shown in this figure. The said pipeline comprises an initial station 8 and three intermediate stations 9, l0 and H, determining four pipeline sections 12, 13, 14 and 15, section 15 ending with a delivery terminal 16 that allows distribution of transported liquids among different users. Curve A, for which the abscissa is in kilometers and the ordinate in meters, shows the altitude profile of the pipeline.

It is observed in FIG. 1 that station 9 comprises, in series, a pump 24 with variable pitch blades of the type described in the aforesaid copending US. patent application Ser. No. 127,506, in series with a centrifugal pump 22 of standard type, driven by its motor. Pump 24 is driven by a motor 23, and the pitch of the blades is determined by a servo motor 17. A discharge pressure sensor is connected by an electric lead 25 to a regulation device 26 which belongs to station 9. An intake pressure sensor 18 of the station is also connected by a line 27 to device 26. Finally, a flow sensor 19 is connected by a line 28 to said device 26. The output of device 26'is connected to servo motor 17 by a conductor 29.

It is to be observed that pumping station 10 is identical in its makeup to pumping station 9. On the other hand, pumping station 11 is characterized in that it has two variable blade pumps 24 in series.

Initial station 8 is not shown. It has the same arrangement as station 9 or station 10.

A process of regulation of this pipeline in its normal use regime will now be described.

Let us assume that at instant 0 the flow and all conditions are constant in the pipeline, with a hydrocarbon of given viscosity and density circulating in the various sections of the pipeline. Pumps 22 all turn at their normal operating speed driven by their respective motors, and pumps 24 are also driven at a constant velocity. Pitch angle i of the blades of the several pumps 24 is determined as a function of pumping conditions in each of the stations, so as to furnish the required pressures. In this functional state, we assume that section 13 between stations 9 and 10 is the one in which there are the most disadvantageous flow conditions. In other words, we assume that it is in the said section 13 that pumping station 9 discharges with a pressure equal to the maximum limit pressure that can be tolerated by the mechanical resistance of the conduit of said section 13. FIG. 2 shows in solid lines curve B corresponding to this hydrocarbon, for this flow state. Feed head at station 8 is a, and the head or pressure delivered by station 8 is equal to b, i.e., 450 meters. The intake pressure of station 9 is c, and station 9 discharges at head d which corresponds to the maximum limit pressure of said station 9. Similarly, e, f, g, h designate respectively the intake heads and the discharge head at stations 10 and 11. k designates the arrival head at terminal 16. For the sake of simplicity we assume that pressure k is supposed to be held constant in all cases.

We now assume that at instant I) there is introduced in initial station 8 a new hydrocarbon of the same density but with higher viscosity. Consequently, to sustain the flow at the same value as before, it is necessary to modify the pitch of the blades of pump 24 of station 8 to deliver a pressure higher than b. As the more viscous hydrocarbon advances in conduit 12 and drives ahead of it the less viscous hydrocarbon, the pressure delivered by station 8 has to increase and at a certain moment it will reach the maximum limit pressure of station 8, which is sensed by sensor 20 (pressure) of station 8. We see then that the characteristic curve of section 12 is represented by the portion of the curve b'i in broken lines descending from the value of the maximum pressure limit b of station 8 and meeting at point i the curve bc that corresponded to the former hydrocarbon. In this situation, about two-thirds of section 12 is filled with more viscous hydrocarbon, the last third still containing less viscous liquid. From this moment on it is section 12 that becomes the section where conditions are least favorable. Consequently, as the viscous liquid continues to advance in conduit 12, station 8 will now have to reduce its flow gradually, to reduce the charge loss in section 12 so that, starting from the maximum limit pressure it will be possible to attain nonetheless the minimum pressure 0 that is required at the station. When the more viscous hydrocarbon has entirely occupied section 12, the curve that represents the flow is then represented by the dot and dash line b c that corresponds to the reduced flow.

This behavior of station 8 can be obtained entirely automatically, slaving the functioning of station 8 so that it does not exceed the limit value of maximum pressure.

Of course, the reduction of flow caused by the behavior of station 8 automatically reacts on the other stations that now pump with a lower flow, this being effected by modification of the pitch of the blades of pumps 24 of the different stations 9, 10, 11, to reduce the pressure delivered by each station. The dashed lines show the flow in the different sections. In other words, the flow is imposed by the situation prevailing in section 12, i.e., the flow imposed by station 8.

However, when the more viscous liquid continues to advance and now penetrates into section 13, station 9 will now have progressively to increase its pressure from the lowest value d that it had reached. When the discharge pressure of station 9 reaches maximum pressure limit d, it is again section 13 that will be in the most unfavorable position, and station 9 will then have to reduce its flow by corresponding modification of the pitch of the blades of pump 24 of said station. This flow reduction will be felt in stations 8, 10 and 11, and the said stations will again adapt to this new flow by modifying the pitch of blades of pumps 24 belonging to them. The new flow state has not been indicated in FlG. 2, but it is to be understood that the flow has now reached a still lower value corresponding to conditions that are tolerable in section 13.

If we now assume that there is again introduced in station 8 a less viscous hydrocarbon, when this new bydrocarbon reaches section 13, station 9 will be able to increase its flow again as section 13 fills with less viscous liquid, which will oblige stations 14 and 15 to increase their flow. Because said stations 10 and 11 pump a more viscous liquid, one of them will reach the maximum limit discharge pressure, and it will then be its section that will be in the least favored position, imposing its flow on the rest of the pipeline.

In summary, in a described embodiment, the process of the invention consists in determining the section in which the flow is effected in the least favored way, in causing the pumping station of this section to pump with modification of the angle or orientation of the blades so as to produce the maximum limit pressure in the said section, and in imposing the flow thus produced on other stations, modifying correspondingly the pitch of the blades of the pumps of the other said statron.

This process can be developed in a decentralized arrangement in the pipeline of FIG. 1, in the following way: when the discharge pressure sensor detects a pressure less than the maximum limit pressure, regulation means 26 seeks to sustain the flow measured in flow sensor 19. This can be attained, for example, by provision in each station of a regulator 26 which receives suction pressure via and discharge pressure via 18 and which controls the blade pitch to maintain the flow through the station between the limits materialized by suction and discharge pressostats whose reference points are regulated as a function of the N P S H on the one hand and the maximum limit admissible pressure in the downstream pipe on the other.

The management of the pipeline may also be effected in a totally centralized way as shown in FIG. 3, in which it is to be noted that the different sensors are joined to a centralized device 21. When a maximum limit pressure is reached in one of the stations at 20, there is imposed on the other stations a blade pitch that respects the flow corresponding to the said limit value of maximum pressure in the station working in an unfavorable situation. When the pressure starts to go up in another station and then reaches the maximum pressure limit, the new flow that results therefrom is then imposed on all the other stations.

Generally speaking, in the last section of the pipeline 15 which ends at terminal 16 the attempt is made to obtain either a certain flow or a certain pressure. In the former case, if a certain flow is sought, it is necessary of course that the flow in the terminal not be greater than the maximum flow capable of passing through the most unfavored section, as seen above. If a given delivery pressure at the terminal is taken as the constraint, the effort will be then made to have the flow as great as possible.

On the other hand, in the case in which it is sought to impose a flow on the pipeline so as to obtain the desired flow at the terminal, the invention provides a regulation process that differs from the above process. It must of course be assumed that the flow in the terminal is such that in no section will it be necessary to attain the maximum limit pressure of the section, without which we would be brought back to the case of regulation described above. On the contrary, this second case of regulation is more simple because since the flow is fixed in advance, all means of regulation of a station will calculate the pressure that the station must necessarily establish in the pipeline section as a function of the viscosity of the liquids passing through the section, to get the sought flow.

The invention also relates to a process which allows constant utilization of the station output, in a pumping station such as, for example, station 11 comprising at least two pumps 24.

Assume that a pipeline station such as station 11 comprises at least two pumps 24, either in series or in parallel.

In the regulation process mentioned before, the sought for flow conditions impose flow and pressure values in a specific section and consequently the flow and pressure of each pumping station are imposed.

Referring to FIG. 4, when a flow and a pressure are to be established in the section fed by the said station which has at least two variable blade pumps, the conditions are often such that the two variable blade pumps have to be driven in operation or that even if only one variable blade pump has to be driven, the point of the characteristic that is fixed by the value of the flow and pressure corresponds to a weakened output of the said pump. in these conditions, putting the two pumps 24 into action, it is possible to modify the blades of the different pumps so as to obtain a maximum output of the two variable blade pumps of the station, those fixed vane pumps of standard type that may be present in the station being driven at their normal speed.

Thus, for example, if the two pumps 24 of the station have to pump so as to furnish the pressure and flow represented by point E, we see that a single pump could manage it with a blade setting greater than 25, for example 28", but with an extremely low output. it is then preferable to run the two pumps 24 of the station 11 so that each will furnish a flow and a pressure as represented at D, i.e., the same flow but at half the pressure of E, the sum of the two pressures D then furnishing the final pressure E. It is to be observed that the position of point D is such that an angle i of about 7 is sufficient and allows pumping with the two pumps with an efficiency of the order of 87 percent.

It may advantageously be provided, in device 26, that there be regulation of the efficiency in the scope of one station such as station 11 having at least two pumps 24 with variable blades, a cam surface corresponding to the efficiency curves of a pump of the station. With reference to FIG. 4, such a surface can be obtained by giving each point, in addition to its abscissa Q and its ordinate H a vertical level corresponding to the efficiency. The efficiency curves, for example, curves percent,

87 percent, 89 percent and others, are then curves with a level equal to the said surface in the form of a hill. Above the said surface, a carriage is movable because of suitable rails, as much in the direction of abscissa Q as in the direction of ordinate H, the position of the carriage in the abscissa being determined by the measured value of the flow by means of the corresponding sensor while the position of the carriage on the ordinate H is determined by the value of pressure produced by one of pumps 24 of the station. On said carriage there slides vertically a sensing device with a wheel in contact with said cam surface. The position in height of the sensor in the carriage is detected by suitable means and thus furnishes an indication of the pump efficiency. A second cam surface can be provided, corresponding to the efficiency cruves of the assembly of the two pumps 24 of the station, and it will be readily understood that such a surface will simply be an extrapolation of the cam surface corresponding to FIG. 4. A corresponding carriage with a sensor can be provided on this second cam surface, and a mechanism can be provided, such that when, on the cam surface of a single operating pump 24, the sensor detects an efficiency that is less than a specific value corresponding for example to the curve of intersection of two surfaces in a same trirectangular of reference coordinates, the second pump 24 is also set going and it is then the sensor of the second cam surface that indicates the bulk efficiency of the two pumps. When the bulk efficiency thus indicated goes down to an excessively low value, the said second pump is then stopped and the process is returned to the initial situation.

As a modification, the cam surface can be replaced by a mathematical model of the characteristic surfaces of the pumps and the associated efficiency curves, this mathematic model being materialized in a logical computer, either analog or digital, connected to the different sensors of the station, to determine the efficiency and stop or start-up pumps 24 to get the maximum efficiency at the station, maintaining the same flow and pressure characteristics.

Refer to FlGS. and 6, there is now to be described a process for starting a pipeline containing mixed stations such for example as 9 and 10, i.e., stations comprising at least one variable blade pump 24 and at least one fixed vane pump of standard type 22. For simplification, the process will be described for a station such as 9, having a variable blade pump 24 and fixed vane pump 22.

[t is known that start-up in conventional pipelines comprising pumping stations with fixed centrifugal pumps presents great difficulties because these pumps do not allow a sufficiently smooth gradual rise in pressure. Consequently, considerable power is called on in the start up, and the flows are actuated with jolts that are prejudicial to the whole installation.

Pumping station 110 of a pipeline that is shown corresponds substantially to station 10 but it is developed in a less schematic form. The station has first of all a centrifugal pump with fixed vanes 122 between sections 113 and 114 interconnected by valves 129, said centrifugal pump being disposed in a branching on conduit 127, the return of the pump on the conduit being effected by a conduit 128. On conduit 127 there is a suction valve 130, and on conduit 128 a discharge valve 131. Conduit 128 has a branch with a valve 132 that ends at the suction side of pump 124. The discharge of said pump via discharge valve 133 is taken by a conduit 134 to section 114. The discharge pressure sensor is connected to the regulation device of station 126 which comprises, on line 125, a pressure regulator 134, of a known type, which, when it receives the pressure detected at 120, compares it to a reference pressure and as a function of the separation that may exist, sends a command via a logical circuit 135 to servo motor 117 on line 127. Two supplementary conductors 136 and 137 indicate to logical circuit 135 if the blades are in a completely opened or completely closed position. Three conductors 138, 139 and 140, respectively, actuate intake valve 130, pump motor 122 and discharge valve 131.

In accordance with the invention, the start up of the station is effected as follows:

Discharge valves 131, 133 and valve 129 are closed. Pump 24 is then started with its blades forming an angle close to the maximum (1' 0). When the normal speed of said pump 24 is attained, at instant 0 the discharge valve 131 is opened and a gradual increase of the angle of the pump blades is begun. Curve 24 of FIG. 5 shows that at instant 0 the pressure gradually increases to a valve p at instant E This pressure p, is substantially equal to the total head furnished by pump 22 when it is set going.

Before instant t fixed vane pump 22 is started, which rises rather rapidly in pressure according to its own characteristic. At instant I, (or after, if it is desired) valve 133 is opened and valve 129' is closed. Simultaneously, while pump 24 is kept at its normal speed, its blades are rapidly closed to angle 0, at a speed that substantially compensates the abrupt rise in pressure due to pump 22. As a result, the sum of the pressures of pumps 24 22 presents here a horizontal plateau between instant I, and instant t at which the pressure due to pump 22 is stabilized. At this moment if it is desired that pump 24 also contribute to increase the total pressure, its blades are again gradually opened, and there is finally obtained a total pressure p In the situation in which the station comprises a pump 22 and a pump 24 disposed in parallel instead of in series, it is understood that the regulation for orientable blade pump 24 will consist in ensuring a pumping head identical to that of the fixed vane pump, while adjusting the total flow since the individual flows of the two pumps are summed. In this case the starting sequence will consist in first starting pump 24 with a blade pitch of zero and then in gradually opening the blades until a specific flow and pressure is established. From this moment, the conventional centrifugal pump 22 is started with its discharge valve closed. The discharge valve is then opened and, with maintenance of the pressure, the angles of the blades are closed sufficiently to reduce the flow while the flow of the fixed vane pump is increased.

The invention also relates to a process for preventing the hammer effect that can develop in conduits and especially in pipelines. It is known that such hammer often appears in accidental closure of a valve, for example, in the terminal and the whole liquid column is thus abruptly blocked. A wave of excess pressure then rises upstream at a speed close to that of sound in the liquid. In already existing pipelines wave front sensors are provided, these devices being known, which detect hammer waves and transmit them by a teletransmission system to the upstream stations. Up to the present, there has been provided as solution for hammer, the sudden stop of a pumping group of the station toward which the hammer is travelling. This presents a grave disadvantage because of the sudden stop of the pump motors and of all the transmission and on the other hand, because of the necessity ultimately to restart the pumps, which wears the motors considerably. Besides, the sudden stop of the pumps of a pumping station often causes a hammer that moves in the upstream station and, in a cascade effect, it is often necessary successively to close all the pumping stations.

According to the invention, when there is hammer, this hammer is detected by a standard hammer detector. Instead of stopping one or more pumps of the station toward which the hammer is travelling, the blade angle is then closed so as to diminish considerably the pressure of pump 24 before the arrival of the hammer. The excess pressure provoked by the hammer will then be added to a pressure that is already reduced, so that the total pressure will not be dangerous for the installation. Moreover, the motor continues to turn at its speed and there is thus avoided, after liquidation of the hammer, the necessity to restart the pump motors.

It should now be apparent that the process for the regulation of the flow in conduits as described hereinabove possesses each of the attributes set forth in the specification under the heading Summary of the Invention hereinbefore. Because the process for the regulation of the flow in conduits can be modified to some extent without departing from the principles of the invention as they have been outlined and explained in this specification, the present invention should be understood as encompassing all such modifications as are within the spirit and scope of the following claims.

What is claimed is:

l. A process for regulating fluid flow in a pipeline that includes at least two sections, each having a characteristic maximum internal pressure to which it may be subjected without experiencing an unacceptable probability of mechanical failure and each being headed by a pumping station having at least one variable pitch bladed rotary pump for increasing pressure on the fluid forwarded thereto in the pipeline, comprisiontinuously detecting which one section is being subjected to an internal pressure nearest its said characteristic maximum; maintaining the pitch of the blades of the respective pump of the station of said one section to tend to sustain said nearest internal pressure; and

pivoting the blades of the respective pump at the station of at least one other section to accommodate the rate of flow through said one section.

2. A process for regulating fluid flow in a pipeline that includes at least a first and second sections, each having a characteristic maximum internal pressure to which it may be subjected without experiencing an unacceptable probability of mechanical failure and each being headed by a pumping station having at least one variable pitch bladed rotary pump for applying pressure on the fluid forwarded thereto in the pipeline, comprising:

. 65 continuously detecting Wl'llCh one of the two sections is being subjected to an internal pressure nearest its said characteristic maximum;

when it is said first section, maintaining the pitch of the blades of said pump for the first section to tend to sustain said nearest internal pressure in said first section and pivoting the blades of said pump of the 5 second section to accommodate the rate of flow through said first section; and

when it becomes said second section, maintaining the pitch of the blades of said pump for the second section to tend to sustain said nearest internal pressure in said second section and pivoting the blades of said pump of the first section to accommodate the rate of flow through said second section.

3. A process for regulating fluid flow in a pipeline that includes at least a first and a second section and leading to a terminal, each section having a characteristic maximum internal pressure to which it may be subjected without experiencing an unacceptable probability of mechanical failure and each being headed by a pumping station having at least one variable pitch bladed rotary pump for applying pressure on the fluid being forwarded through the pipeline to the terminal, comprising:

so long as it can be accomplished without exceeding the characteristic maximum internal pressure for any section, pitching the blades of said pumps to obtain in each of said stations the pressure necessary to cause said fluid to reach the terminal at a predetermined rate;

continuously monitoring the pressure in said stations and when trying to achieve said predetermined rate would require exceeding said characteristic maximum internal pressure of any one section, temporarily flattening the pitch of the blades of said pump for that one section sufficiently to avoid exceeding said characteristic maximum internal pressure in that one section, and

pivoting the blades of said pump of at least another of said sections to accommodate the rate of flow through said one section, even though this may temporarily result in a lower flow rate at said terminal than said predetermined rate.

4. A process for regulating fluid flow in a pipeline that includes at least one section headed by a pumping station having at least two variable pitch bladed rotary pumps for applying pressure on the fluid being forwarded through the pipeline section, comprising these steps aimed at providing a predetermined flow rate through the pipeline section:

starting a first of said pumps and pitching its blades at an angle which will provide said predetermined flow rate if it is within the capacity of that pump to do so;

detecting the actual flow rate then provided by that pump and, if it is less than said predetermined flow rate, then starting the second of said pumps and adjusting the pitch of the blades of both said pumps to produce said predetermined flow rate. I 5. A process for regulating fluid flow in a pipeline that includes at least one section headed by a pumping station provided with at least one fixed pitch bladed rotary pump, at least one variable pitch bladed rotary pump and a discharge valve for isolating the pressure side of the fixed pitch bladed pump from the pipeline, during start-up, said process comprising:

starting the variable pitch bladed pump with a closed blade angle until a normal operating rate of rotation for that pump is obtained;

gradually opening the angle of the blades thereof to establish a pressure;

starting the fixed pitch bladed pump with the discharge valve closed until a normal operating rate of rotation for that pump is obtained; then, simultaneously, opening said discharge valve and partially closing the angle of the blades of the variable pitch bladed pump by an amount sufficient to effect a reduction of pressure substantially equal to the increase in pressure furnished by the fixed pitch bladed pump. 6. A process for regulating fluid flow in a piepline that includes at least one section headed by a pumping station having at least one variable pitch bladed rotary pump for applying pressure on the fluid being forwarded through the pipeline section, comprising these steps aimed at extinguishing the upstream propagation of hammering, comprising:

operating the pump with the blades set at a pitch to maintain a pressure that does not exceed the maximum internal pressure to which the pipeline of that section may be subjected without experiencing an unacceptable probability of mechanical failure;

upon detecting the appearance of hammering downstream from said station, reducing the pitch of said blades to effect a lowering of pressure sufficient, when considered with the additional pressure resulting during the hammering, to make the total pressure within the section still lie within said maximum.

7. Apparatus for the regulation of flow in a pipeline, comprising: at least two pumping stations upstream of a corresponding number of sections, each comprising at least one pump with a casing, a rotor, bearing to support said rotor in rotation about its longitudinal axis in said case, means to turn said rotor about said axis, a plurality of blades disposed between the rotor and the casing, shaft means for the mounting of each blade on said rotor for a movement of pivoting about its longitudinal axis, said shaft means, collectively, having their longidutinal axes arranged on a cone of revolution coaxial with said rotor, means associated with the said rotor including servo motors, to pivot said blades with reference to said rotor about said axes, means for measuring parameters of hydraulic flow, disposed in the said pipeline, and means for regulation connecting said measuring means to said servo motors to effect a movement of pivoting of said blades in response to measurements effected by said measuring means, whereby the following operation may be conducted:

detecting that one of the said pipeline sections in which flow is effected in the most unfavored way;

maintaining the pitch of said blades in said station corresponding to said least favored section to sustain a pressure corresponding to the value of the maximum admissible limit pressure for said least favored section; and

pivoting said blades of the other said stations to maintain the flow that results from the flow in the said least favored section.

8. Apparatus for regulation of the flow in a pipeline with a terminal, comprising:

at least two pumping stations upstream of a corresponding number of sections each comprising at least one pump with a casing, a rotor, hearings to support said rotor in rotation about its longitudinal axis in said casing, means to turn said rotor about said axis, a plurality of blades disposed between said rotor and said casing, shaft means for mounting of each blade on said rotor for a pivoting movement about its longitudinal axis, said shaft means collectively having their longitudinal axes disposed on a cone of revolution coaxial with said rotor, means associated with the said rotor including servo motors to pivot said blades with reference to said rotor about said axes, measurement means for determining parameters of hydraulic flow disposed in said pipeline, regulation means connecting said measurement means to said servo motors to effect a movement of pivoting of said blades in response to measurements effected by said measuring means, whereby the following operation may be conducted:

determining the desirable flow in said terminal;

modifying the pitch of the blades of said stations to obtain in each of said stations the pressure necessary to cause said flow to pass in the associated section; detecting if in said sections the pressure reaches a maximum limit tolerable value for said section;

and if such pressure has been detected, maintaining the blades of the station of said section so as to sustain said pressure; and

modifying the pitch of the blades of said other stations so as to respect the new flow thus imposed.

9. Apparatus for regulation, to increase the pumping output in a conduit comprising: at least one pumping station with at least two pumps, each having a casing, a rotor, bearings to support said rotor in rotation about its longitudinal axis in said casing, means to turn said rotor about said axis, a plurality of blades disposed between said rotor and said casing, shaft means for mounting each blade on said rotor for a pivoting movement about its longitudinal axis, said shaft means collectively having their longitudinal axes disposed on a cone of revolution coaxial with said rotor, means associated with said rotor including servo motors to pivot said blades with reference to said rotor about said axes, means for measurement for hydraulic flow parameters disposed in the said conduit, and means for regulation connecting said measurement means to the servo motors to effect a pivoting movement of said blades in response to measurements effected by said measuring means, whereby the following operation may be conducted:

starting the first of the said pumps;

adjusting the pitch of the blades of the said pump to obtain a sought-for flow state;

detecting the output of said pump with the blades thus tilted;

comparing the output value as detected with a preestablished value and, if the said output is less than the said value, starting at least a second of said pumps and adjusting the pitch of the said operating pumps to obtain the desired flow state.

10. Apparatus for regulation of the start up in a conduit, comprising: at least one pumping station with at least one pump with fixed vanes and a discharge valve and at least one pump comprising a casing, a rotor, bearings to support said rotor in rotation about its longitudinal axis in said casing, means to turn said rotor about said axis, a plurality of blades disposed between said rotor and said casing, shaft means for mounting each blade on said rotor for a pivoting movement about its longitudinal axis, said shaft means collectively having their longitudinal axes disposed on a cone of revolution coaxial with said rotor, means associated with said rotor including servo motors for pivoting said blades with reference to said rotor about said axes, means for measurement of hydraulic flow parameters disposed in said conduit and regulation means connecting said measurement means to the servo motors to effect a pivoting movement of said blades in response to measurements effected by said measurement means, whereby the following operation may be conducted:

starting the said pump with variable blades with a closed blade angle until a normal rate of rotation of the pump is obtained; gradually opening the angle of said blades to establish a pressure; starting the said pump with fixed vanes with the said discharge valve closed until the normal rate of rotation of said pump is obtained; opening the said discharge valve; and simultaneously closing the blades of the said variable blade pump to cause a reduction in pressure substantially equal to the increase in pressure furnished by the fixed vane pump when said valve is opened. 11. Apparatus for regulation of flow in case of hammer in a conduit, comprising: at least one pumping station with at least one pump, comprising a casing, 21 rotor, bearings to support said rotor in rotation about its longitudinal axis in said casing, means to turn said rotor about said axis, a plurality of blades disposed between said rotor and said casing, shaft means for mounting each blade on said rotor for a movement of pivoting about its longitudinal axis, said shaft means collectively having their longitudinal axes disposed on a cone of revolution coaxial with said rotor, means associated with said rotor including servo motors to pivot said blades with reference to said rotor about said axes, means for measurement of hydraulic flow parameters, disposed in said conduit, means for regulation connecting said measuring means with said servo motors to effect a movement of pivoting of said blades in response to measurements made by said measuring means, said station discharging into a section downstream thereof, whereby the following operation may be conducted:

detecting the appearance of hammer downstream of said station; and reducing the pitch of said blades to cause a lowering or pressure sufficient, under the influence of the excess pressure of the hammer, to make the total pressure not exceed a preestablished safety pressure valve. 

1. A process for regulating fluid flow in a pipeline that includes at least two sections, each having a characteristic maximum internal pressure to which it may be subjected without experiencing an unacceptable probability of mechanical failure and each being headed by a pumping station having at least one variable pitch bladed rotary pump for increasing pressure on the fluid forwarded thereto in the pipeline, comprising: continuously detecting which one section is being subjected to an internal pressure nearest its said characteristic maximum; maintaining the pitch of the blades of the respective pump of the station of said one section to tend to sustain said nearest internal pressure; and pivoting the blades of the respective pump at the station of at least one other section to accommodate the rate of flow through said one section.
 2. A process for regulating fluid flow in a pipeline that includes at least a first and second sections, each having a characteristic maximum internal pressure to which it may be subjected without experiencing an unacceptable probability of mechanical failure and each being headed by a pumping station having at least one variable pitch bladed rotary pump for applying pressure on the fluid forwarded thereto in the pipeline, comprising: continuously detecting which one of the two sections is being subjected to aN internal pressure nearest its said characteristic maximum; when it is said first section, maintaining the pitch of the blades of said pump for the first section to tend to sustain said nearest internal pressure in said first section and pivoting the blades of said pump of the second section to accommodate the rate of flow through said first section; and when it becomes said second section, maintaining the pitch of the blades of said pump for the second section to tend to sustain said nearest internal pressure in said second section and pivoting the blades of said pump of the first section to accommodate the rate of flow through said second section.
 3. A process for regulating fluid flow in a pipeline that includes at least a first and a second section and leading to a terminal, each section having a characteristic maximum internal pressure to which it may be subjected without experiencing an unacceptable probability of mechanical failure and each being headed by a pumping station having at least one variable pitch bladed rotary pump for applying pressure on the fluid being forwarded through the pipeline to the terminal, comprising: so long as it can be accomplished without exceeding the characteristic maximum internal pressure for any section, pitching the blades of said pumps to obtain in each of said stations the pressure necessary to cause said fluid to reach the terminal at a predetermined rate; continuously monitoring the pressure in said stations and when trying to achieve said predetermined rate would require exceeding said characteristic maximum internal pressure of any one section, temporarily flattening the pitch of the blades of said pump for that one section sufficiently to avoid exceeding said characteristic maximum internal pressure in that one section, and pivoting the blades of said pump of at least another of said sections to accommodate the rate of flow through said one section, even though this may temporarily result in a lower flow rate at said terminal than said predetermined rate.
 4. A process for regulating fluid flow in a pipeline that includes at least one section headed by a pumping station having at least two variable pitch bladed rotary pumps for applying pressure on the fluid being forwarded through the pipeline section, comprising these steps aimed at providing a predetermined flow rate through the pipeline section: starting a first of said pumps and pitching its blades at an angle which will provide said predetermined flow rate if it is within the capacity of that pump to do so; detecting the actual flow rate then provided by that pump and, if it is less than said predetermined flow rate, then starting the second of said pumps and adjusting the pitch of the blades of both said pumps to produce said predetermined flow rate.
 5. A process for regulating fluid flow in a pipeline that includes at least one section headed by a pumping station provided with at least one fixed pitch bladed rotary pump, at least one variable pitch bladed rotary pump and a discharge valve for isolating the pressure side of the fixed pitch bladed pump from the pipeline, during start-up, said process comprising: starting the variable pitch bladed pump with a closed blade angle until a normal operating rate of rotation for that pump is obtained; gradually opening the angle of the blades thereof to establish a pressure; starting the fixed pitch bladed pump with the discharge valve closed until a normal operating rate of rotation for that pump is obtained; then, simultaneously, opening said discharge valve and partially closing the angle of the blades of the variable pitch bladed pump by an amount sufficient to effect a reduction of pressure substantially equal to the increase in pressure furnished by the fixed pitch bladed pump.
 6. A process for regulating fluid flow in a piepline that includes at least one section headed by a pumping station having at least one variable pitch bladed rotary pump for applyinG pressure on the fluid being forwarded through the pipeline section, comprising these steps aimed at extinguishing the upstream propagation of hammering, comprising: operating the pump with the blades set at a pitch to maintain a pressure that does not exceed the maximum internal pressure to which the pipeline of that section may be subjected without experiencing an unacceptable probability of mechanical failure; upon detecting the appearance of hammering downstream from said station, reducing the pitch of said blades to effect a lowering of pressure sufficient, when considered with the additional pressure resulting during the hammering, to make the total pressure within the section still lie within said maximum.
 7. Apparatus for the regulation of flow in a pipeline, comprising: at least two pumping stations upstream of a corresponding number of sections, each comprising at least one pump with a casing, a rotor, bearing to support said rotor in rotation about its longitudinal axis in said case, means to turn said rotor about said axis, a plurality of blades disposed between the rotor and the casing, shaft means for the mounting of each blade on said rotor for a movement of pivoting about its longitudinal axis, said shaft means, collectively, having their longidutinal axes arranged on a cone of revolution coaxial with said rotor, means associated with the said rotor including servo motors, to pivot said blades with reference to said rotor about said axes, means for measuring parameters of hydraulic flow, disposed in the said pipeline, and means for regulation connecting said measuring means to said servo motors to effect a movement of pivoting of said blades in response to measurements effected by said measuring means, whereby the following operation may be conducted: detecting that one of the said pipeline sections in which flow is effected in the most unfavored way; maintaining the pitch of said blades in said station corresponding to said least favored section to sustain a pressure corresponding to the value of the maximum admissible limit pressure for said least favored section; and pivoting said blades of the other said stations to maintain the flow that results from the flow in the said least favored section.
 8. Apparatus for regulation of the flow in a pipeline with a terminal, comprising: at least two pumping stations upstream of a corresponding number of sections each comprising at least one pump with a casing, a rotor, bearings to support said rotor in rotation about its longitudinal axis in said casing, means to turn said rotor about said axis, a plurality of blades disposed between said rotor and said casing, shaft means for mounting of each blade on said rotor for a pivoting movement about its longitudinal axis, said shaft means collectively having their longitudinal axes disposed on a cone of revolution coaxial with said rotor, means associated with the said rotor including servo motors to pivot said blades with reference to said rotor about said axes, measurement means for determining parameters of hydraulic flow disposed in said pipeline, regulation means connecting said measurement means to said servo motors to effect a movement of pivoting of said blades in response to measurements effected by said measuring means, whereby the following operation may be conducted: determining the desirable flow in said terminal; modifying the pitch of the blades of said stations to obtain in each of said stations the pressure necessary to cause said flow to pass in the associated section; detecting if in said sections the pressure reaches a maximum limit tolerable value for said section; and if such pressure has been detected, maintaining the blades of the station of said section so as to sustain said pressure; and modifying the pitch of the blades of said other stations so as to respect the new flow thus imposed.
 9. Apparatus for regulation, to increase the pumping output in a conduit comprising: at least one Pumping station with at least two pumps, each having a casing, a rotor, bearings to support said rotor in rotation about its longitudinal axis in said casing, means to turn said rotor about said axis, a plurality of blades disposed between said rotor and said casing, shaft means for mounting each blade on said rotor for a pivoting movement about its longitudinal axis, said shaft means collectively having their longitudinal axes disposed on a cone of revolution coaxial with said rotor, means associated with said rotor including servo motors to pivot said blades with reference to said rotor about said axes, means for measurement for hydraulic flow parameters disposed in the said conduit, and means for regulation connecting said measurement means to the servo motors to effect a pivoting movement of said blades in response to measurements effected by said measuring means, whereby the following operation may be conducted: starting the first of the said pumps; adjusting the pitch of the blades of the said pump to obtain a sought-for flow state; detecting the output of said pump with the blades thus tilted; comparing the output value as detected with a preestablished value and, if the said output is less than the said value, starting at least a second of said pumps and adjusting the pitch of the said operating pumps to obtain the desired flow state.
 10. Apparatus for regulation of the start up in a conduit, comprising: at least one pumping station with at least one pump with fixed vanes and a discharge valve and at least one pump comprising a casing, a rotor, bearings to support said rotor in rotation about its longitudinal axis in said casing, means to turn said rotor about said axis, a plurality of blades disposed between said rotor and said casing, shaft means for mounting each blade on said rotor for a pivoting movement about its longitudinal axis, said shaft means collectively having their longitudinal axes disposed on a cone of revolution coaxial with said rotor, means associated with said rotor including servo motors for pivoting said blades with reference to said rotor about said axes, means for measurement of hydraulic flow parameters disposed in said conduit and regulation means connecting said measurement means to the servo motors to effect a pivoting movement of said blades in response to measurements effected by said measurement means, whereby the following operation may be conducted: starting the said pump with variable blades with a closed blade angle until a normal rate of rotation of the pump is obtained; gradually opening the angle of said blades to establish a pressure; starting the said pump with fixed vanes with the said discharge valve closed until the normal rate of rotation of said pump is obtained; opening the said discharge valve; and simultaneously closing the blades of the said variable blade pump to cause a reduction in pressure substantially equal to the increase in pressure furnished by the fixed vane pump when said valve is opened.
 11. Apparatus for regulation of flow in case of hammer in a conduit, comprising: at least one pumping station with at least one pump, comprising a casing, a rotor, bearings to support said rotor in rotation about its longitudinal axis in said casing, means to turn said rotor about said axis, a plurality of blades disposed between said rotor and said casing, shaft means for mounting each blade on said rotor for a movement of pivoting about its longitudinal axis, said shaft means collectively having their longitudinal axes disposed on a cone of revolution coaxial with said rotor, means associated with said rotor including servo motors to pivot said blades with reference to said rotor about said axes, means for measurement of hydraulic flow parameters, disposed in said conduit, means for regulation connecting said measuring means with said servo motors to effect a movement of pivoting of said blades in response to measurements made by said measuring means, said station dischaRging into a section downstream thereof, whereby the following operation may be conducted: detecting the appearance of hammer downstream of said station; and reducing the pitch of said blades to cause a lowering or pressure sufficient, under the influence of the excess pressure of the hammer, to make the total pressure not exceed a preestablished safety pressure valve. 